Bipolar junction transistors with nanosheet structures and methods for manufacturing the same

A semiconductor device, comprising:

• a substrate having a first conductivity;
• a first well embedded in the substrate and having a second conductivity;
• a second well embedded in the first well and having the first conductivity;
• a third well embedded in the first well and having the second conductivity;
• a first subset of stacks formed over the second well, wherein the first subset of stacks includes a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked on top of one another, and wherein both the first and second semiconductor layers are doped with the first conductivity;
• a second subset of stacks formed over the substrate, wherein the second subset of stacks include a plurality of third semiconductor layers and a plurality of fourth semiconductor layers alternately stacked on top of one another, and wherein both the third and fourth semiconductor layers are doped with the first conductivity;
• and
• a third subset of stacks formed over the third well, wherein the third subset of stacks include a plurality of fifth semiconductor layers and a plurality of sixth semiconductor layers alternately stacked on top of one another, and wherein both the fifth and sixth semiconductor layers are doped with the second conductivity.

A method for manufacturing semiconductor devices, comprising:

• forming a plurality of stacks protruding from a substrate that has a first conductivity, wherein each of the plurality of stacks extends in a first lateral direction and includes a plurality of first semiconductor layers and a plurality of second semiconductor layers alternately stacked on top of one another;
• defining a first well in the substrate that has a second conductivity, wherein the first well extends beneath a first subset of the stacks, a second subset of the stacks, and a third subset of the stacks;
• defining a second well in the first well that has the first conductivity, and a third well and a fourth well in the substrate, wherein the second well extends beneath the first subset of the stacks, the third well extends beneath a fourth subset of the stacks, and the fourth well extends beneath a fifth subset of the stacks;
• growing a first epitaxial structure, a second epitaxial structure, and a third epitaxial structure from the first subset of stacks, the fourth subset of stacks, and the fifth subset of stacks, respectively, wherein the first epitaxial structure, the second epitaxial structure, and the third epitaxial structure have the first conductivity;
• and
• growing a fourth epitaxial structure and a fifth epitaxial structure from the second subset of the stacks and the third subset of the stacks, respectively, wherein the fourth epitaxial structure and the fifth epitaxial structure have the second conductivity.